Geographic Range

Southern river otters, Lontra provocax, are only found in central and southern Chile and parts of Argentina. This species has been exterminated from much of its range in Chile by hunting. In Argentina, it is found along the Andes from Tierra del Fuego all the way to the southern part of Neuquen province (Otternet, 1998).

Habitat

L. provocax inhabits both marine and fresh waters. It is found on rocky coasts and in protected canals in areas where there are few waves. It does not live in open coastal areas, but instead prefers coastal and freshwater environments with dense vegetation (Redford and Eisenberg, 1992).

Physical Description

L. provocax is a medium sized otter. It ranges from 1000 mm to 1160 mm in total length. Its tail is 350 to 460 mm long. These otters possess webbed feet with strong claws. Their hair has a velvety texture. The guard hairs range in length from 15 to 17 mm, and the under fur is 7 to 8 mm long. The dorsum is a very dark brown, which strongly contrasts with the silvery whitish ventrum. Their nose is diamond-shape with the bottom corner squared off (Otternet, 1998).

Development

See Reproduction.

Reproduction

The mating system of this species has not been reported.

River otters typically breed in the winter and spring, with births taking place the following year. Because there is a delay between mating and implantation of the fertilized eggs, there can be a great variability in the length of pregnancy. Although gestation has been reported to be 10-12 months long, actual embryonic development is around two months (Nowak, 1999).

Females have four nipples and produce one to four young each season, but usually produce only one or two young. L. provocax young are born a helpless, blind and scarcely mobile. Young spend their time in the den either suckling or sleeping. The milk is an extremely rich energy source and the young have a high metabolic rate. They open their eyes at approximately one month and begin to eat solid foods at 7 weeks. They begin to swim at about 3 months of age. They are usually capable of catching their own food within 4 months. The young remain with the family group for the first year before they disperse (Chanin, 1985). Reproductive maturity is attained in the second or third year of life.

Lifespan/Longevity

A high proportion of the individuals die before they reach maturity. Only about 1% will survive to reach 10 years of age. Most L. provocax only live a few years (Chanin, 1985).

Range lifespanStatus: wild

10 (high) years

Typical lifespanStatus: wild

3 (low) years

Average lifespanStatus: wild

>3 years

Behavior

L. provocax tends to be found in family groups that consist of the adult female and her young. Males are usually solitary except during the mating season. Males also tend to have a larger home range than family groups. Both sexes of this species are usually active during the night (Chanin, 1985).

Communication and Perception

Food Habits

L. provocax diet varies within the separate habitat types. In a Chilean population, 75% of fecal samples analyzed had fish in them, and 63% had crustaceans. In Argentina the feces showed 99% of scats had crustaceans and only 2% contained fish (Medina, 1998). In addition to fish and crustaceans, southern river otters also eat mollusks and birds (Kruuk, 1995).

Contributors

William Haase (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

freshwater

mainly lives in water that is not salty.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

piscivore

an animal that mainly eats fish

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Chanin, P. 1985. The Natural History of Otters. New York: Facts on File.

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This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.